EMB agar da MacConkey agar: zaɓi da fassarar kafofin girma

Wani ɗalibi ya shafa samfurin ruwa ɗaya a kan faranti biyu. A ɗaya, kolononi masu duhu da sheƙin ƙarfe kore suka bayyana. A ɗayan kuma, kolononi masu ruwan hoda mai haske tare da wani halo mai hazo suka bayyana. An shuka farantin biyu daga bututu ɗaya, an yi musu incubation gefe da gefe, kuma an karanta su a sa'a ɗaya. Ɗalibin ya tambaya wane faranti ne daidai.

Duk farantin biyun daidai ne. Suna amsa tambayoyi daban. Ruɗani yana tasowa ne idan aka ɗauki kafofin girman biyu a matsayin gwaje-gwajen da za a iya musanya su wajen tantance ƙwayoyin hanji. Suna da manufa ɗaya, wato zaɓar kwayoyin enteric masu Gram negative da raba masu fermentation na lactose daga waɗanda ba sa fermentation, amma suna cimma wannan manufa da sinadarai da tsarin gani daban. Da zarar an fahimci waɗannan dabaru biyu, zaɓin faranti da karanta kolononi sukan zama aiki na yau da kullum.

Amsa a taƙaice

EMB agar yana amfani da dyes biyu, eosin Y da methylene blue, waɗanda ke yin ayyuka biyu lokaci guda: suna hana girman Gram positive kuma suna taruwa su yi precipitate a kusa da masu samar da acid mai ƙarfi, suna haifar da kolononi masu duhu, musamman tare da sheƙin ƙarfe kore na Escherichia coli. MacConkey agar kuwa yana raba ayyukan: bile salts tare da crystal violet suna hana Gram positives, lactose yana samar da abin da za a yi fermentation da shi, sannan neutral red yana nuna acid ta hanyar mayar da kolononi ruwan hoda ko ja. Idan aikin shi ne nuna E. coli ta hanyar alamar zato mai bayyana sosai, EMB yana da amfani. Idan kuma aikin shi ne raba masu fermentation na lactose masu ruwan hoda daga nonfermenters marasa launi cikin sauƙi, musamman a tsarin aiki na stool ko urine, MacConkey yawanci ya fi sauƙin karantawa. Babu ɗaya daga cikin farantin da zai iya gano kwayar halitta ta launi kaɗai.

EMB: dyes da ke zaɓi kuma suke nuna sakamako lokaci guda

Tsarin EMB yana haɗa zaɓi da nuna sakamako a cikin molecules ɗaya. Ka'idar ASM ta eosin methylene blue agar ta bayyana EMB a matsayin matsakaicin girma mai zaɓi kuma mai bambance-bambance, inda haɗin dyes ɗin ke hana kwayoyin Gram positive da yawa yayin da fermentation na lactose ke haifar da ɗaukar dye da precipitation. Tsarin Levine na yau da kullum yana ɗauke da peptone, lactose, phosphate, eosin Y, methylene blue, da agar, kamar yadda aka jera a hanyar FDA BAM don Levine EMB agar. A lura cewa wasu tsofaffin girke-girken EMB suna ƙara sucrose tare da lactose, yayin da Levine EMB ke ɗauke da lactose ba tare da sucrose ba, saboda haka a rubuta wane formulation ne dakin gwaje-gwajenku yake amfani da shi.

Karanta EMB yana nufin lura da yadda dyes suke nuna hali. Fermentation na lactose mai ƙarfi yana samar da acid mai yawa wanda ke haifar da precipitation na dye sosai, yana ba E. coli cibiyoyin kolononi masu duhun shuɗi zuwa baƙi kuma, a yanayin gargajiya, sheƙin ƙarfe kore idan aka duba da haske mai dawowa. Masu fermentation masu rauni kamar Enterobacter da Klebsiella yawanci suna girma a matsayin kolononi masu ruwan hoda zuwa purple, masu mucoid, ba tare da wannan sheƙi ba. Nonfermenters kamar Salmonella, Shigella, da Proteus gabaɗaya suna girma a matsayin kolononi marasa launi ko masu ɗan bayyana saboda ba sa samar da gaggawar acid da ke sa dyes su yi precipitate. Gram positives yawanci ana hana su girma, ko da yake ƙarfin wannan hanawa ya bambanta bisa strain da samfurin da ake amfani da shi. Cikakken bayanin sinadaran shirya dye, ciki har da dalilin da methylene blue ke aiki a matsayin cationic stain tun farko, ya dace da wani bayani dabam kan formulations na dye, yayin da mahallin microscopy na gaba ɗaya yana cikin atlas na hanyoyin staining. Wannan labarin yana mai da hankali ne kan zaɓin faranti da karanta sakamako.

Hoton da ke sama na misali ne. Yana nuna tsarin gani da ake tsammani: kolononi masu duhun sheƙi tare da nau'ikan mucoid masu ruwan hoda da nau'ikan masu kodadde a EMB, idan aka kwatanta da nau'ikan masu ruwan hoda da masu kodadde a MacConkey. Yi amfani da shi wajen koyon tsarin, sannan ka tabbatar da kowane hukunci da hotunan controls da kuma bayanin samfurin na ainihin matsakaicin girman da ke kan benchi.

MacConkey: ayyuka dabam-dabam, ƙa'idar gani mafi sauƙi

Tsarin MacConkey yana ba kowane aiki sinadari daban. Ka'idar ASM ta MacConkey agar tana gabatar da tsarin zaɓi da bambance-bambance iri ɗaya, kuma hanyar FDA BAM don MacConkey agar tana jera sinadaran aiki: peptones, lactose, bile salts, salt, neutral red, crystal violet, da agar. Bile salts tare da crystal violet suna hana Gram positives. Lactose yana samar da substrate na fermentation. Neutral red yana aiki a matsayin mai nuna pH, yana juya zuwa ruwan hoda ko ja inda acid ya samu, wani lokaci tare da precipitated bile a kusa da masu fermentation masu ƙarfi.

Ka'idar karantawa an tsara ta ta zama mai sauƙi: ruwan hoda yana nufin mai fermentation na lactose, yayin da mara launi ko kodadde yake nufin nonfermenter. E. coli yana bayyana ruwan hoda zuwa ja, sau da yawa tare da halo na bile precipitate. Klebsiella da Enterobacter suna bayyana ruwan hoda kuma sau da yawa masu mucoid ne saboda capsules ɗinsu. Salmonella, Shigella, Proteus, da sauran Gram negative rods da yawa suna bayyana marasa launi. Wani ƙarin amfani yana da muhimmanci a dakunan koyarwa: bile salts gabaɗaya suna rage swarming na Proteus, don haka samun kolononi da suka ware ya fi sauƙi a MacConkey fiye da kafofin girma marasa zaɓi, ko da yake hanawar ba cikakkiya ba ce kuma akwai madadin marasa salt idan sarrafa swarming shi ne babban abin da ake nema.

Dalilin molecular da ke sa dyes su nuna wannan hali yana da alaƙa da charge da structure. Methylene blue cationic phenothiazine dye ne wanda tsarinsa da halayensa ke bayyana sha'awarsa ga acidic bacterial surfaces, wato irin wannan sha'awa ce ke aiki lokacin da yake yin precipitate a yankunan acid a EMB.

Kwatantawa a taƙaice

Karanta teburin a matsayin hanyar yanke shawara. Idan aikin yana buƙatar ɗalibai su ga bambancin ƙarfin fermentation tare da wani sakamako mai matuƙar bayyana, EMB yana nuna hakan. Idan aikin yana buƙatar rarrabuwa ta sauri tsakanin fermenter da nonfermenter kafin tabbatarwa ta biochemical, MacConkey yana nuna hakan.

Wane matsakaicin girma ya dace da wane samfurin

Ga atisayen ruwa da aka tsara don gano fecal coliform ko E. coli na zato, EMB yana da amfani saboda sheƙinsa yana da sauƙin gane wa da ido. MacConkey ma yana kula da enteric Gram negatives kuma yana da tarihin amfani a gwajin ruwa, amma babu ɗayan farantin da zai maye gurbin hanyar gwajin ruwa ta ƙa'ida, wadda za ta iya kayyade kafofin girma kamar modified mTEC ko MI gwargwadon gwajin. Duba hanyar da dakin gwaje-gwajenku ya wajaba ya bi.

Ga rarrabuwar stool tsakanin fermenters da nonfermenters, MacConkey gabaɗaya ya fi amfani daga cikin biyun. Aikin stool na zahiri don Salmonella ko Shigella yawanci yana ƙara kafofin enteric masu ƙarin zaɓi kamar XLD ko Hektoen enteric maimakon dogaro da MacConkey kaɗai.

Ga koyarwar urine da ke kwaikwayon tsarin aikin clinical, haɗa MacConkey da blood agar. MacConkey yana bayar da rarrabuwar farko ta Gram negative yayin da blood agar ke dawo da kwayoyin da MacConkey ke hana girma. Wannan haɗin ya zama na yau da kullum a bayanan clinical na tsarin culture na urine.

Ga koyar da ka'ida tsantsa, yi amfani da duka biyun. EMB yana koyar da cewa ƙarfin fermentation yana da muhimmanci kuma molecule ɗaya na iya yin ayyuka biyu. MacConkey yana koyar da modular design: selector, substrate, da reporter ana ware su. Ɗaliban da suka streak sanannen E. coli, sanannen Klebsiella aerogenes, da sanannen Salmonella gefe da gefe a kafofin girma biyun ba sa yawan rikita waɗannan dabaru biyu daga baya.

Kura-kuran karantawa da suke maimaituwa kowane zangon karatu

Kuskuren da ya fi yawa shi ne gano kwayar halitta ta launi kaɗai. Ruwan hoda a MacConkey na iya zama E. coli, Klebsiella, Enterobacter, ko wani fermenter. Mara launi na iya zama Salmonella, Shigella, Proteus, Pseudomonas, ko wani nonfermenter. Launi screening phenotype ne da ke jagorantar aikin tabbatarwa kamar Gram stain, oxidase, biochemical panels, ko instrument identification, ba sunan species ba.

Kuskure na biyu shi ne ɗaukar rashin sheƙi a matsayin hujja mai ƙarfi. Wasu ainihin kolononin E. coli, musamman waɗanda suka ware, suna samar da ƙaramin sheƙin ƙarfe ko babu shi. Rashin sheƙi ba ya kawar da E. coli, kuma kasancewar sheƙi ba ya tabbatar da shi. A ɗauki sheƙin a matsayin alamar zato.

Kuskure na uku shi ne kwatanta faranti masu shekaru daban. Masu fermentation na lactose da ke jinkiri na iya zama ruwan hoda a MacConkey bayan dogon incubation, wanda ke dusashe bambancin da ya kamata ya bayyana tsakanin fermenter da nonfermenter. Karanta farantin a sa'ar da dakin gwaje-gwaje ya kayyade kuma ka rubuta lokacin incubation tare da sakamakon.

Kuskure na huɗu shi ne karanta mixed growth a matsayin kwayar halitta ɗaya. Koloni mai ruwan hoda kusa da koloni mara launi yana nuna phenotypes biyu, ba wani matsakaicin phenotype ba. Zaɓi kolononi da suka ware sosai kuma ka yi aiki da kowane morphotype dabam. Mucoid texture ma yana iya ruɗarwa: Klebsiella da Enterobacter dukansu na iya bayyana mucoid, don haka capsule kaɗai ba zai tabbatar da suna ba. Kwayar da a da ake koyarwa da sunan Enterobacter aerogenes yanzu an rarraba ta a matsayin Klebsiella aerogenes, wanda ke bayyana dalilin da tsofaffin charts da sabbin labels suke iya zama kamar sun saba wa juna.

Controls da ƙa'idar ƙarshe

Yi amfani da photographed ko fresh controls a kowane zaman aiki: E. coli don reaction na strong fermenter, Klebsiella aerogenes don mucoid fermentation ba tare da classic sheen ba, wani strain na Salmonella don reaction na colorless nonfermenter, da Staphylococcus aureus don tabbatar da hanawar Gram positive a ainihin samfurin da kuke amfani da shi. Daidaita strain numbers da acceptance criteria da bayanin manufacturer, saboda selectivity yana canzawa da bile, crystal violet, da adadin dye.

Ka tuna jumla ɗaya a benchi. EMB yana amfani da dyes waɗanda suke zaɓi kuma suke bayar da alama, wanda ke ba da wani fitaccen signal na E. coli amma yana buƙatar karatu mai ɗan zurfi. MacConkey yana raba aikin zaɓi da na nuna sakamako, wanda ke ba da sauƙin rarrabawa tsakanin ruwan hoda da kodadde amma da ƙarancin bayanin fermentation. Zaɓi matsakaicin girma wanda dabararsa ta dace da tambayar, tabbatar da launi da gwaje-gwajen da suka dace, sannan farantin biyu ba za su zama masu gogayya ba, za su fara aiki tare.